PROJECT SUMMARY/ABSTRACT: KRAS is among the strongest and most frequently mutated oncogenes in cancer. Tumors with mutant KRAS often become addicted to its presence and in inducible genetic mouse models the sudden removal of mutant KRAS can trigger cancer regressions. However, pharmacological agents capable of inhibiting the most prevalent KRAS mutants have remained elusive and these cancers remain among the most refractory to therapy. The National Cancer Institute's RAS Initiative, in close collaboration with Dr. Frank McCormick's lab at UCSF, recently created an exciting and unpublished new class of inhibitors that covalently bind KRAS and prevent its translocation to the plasma membrane. Intriguingly, these compounds cause KRAS to be degraded, although the detailed mechanism remains unclear. We hypothesize that pharmacological inhibition of KRAS will be therapeutic in cancers driven by KRAS mutations and that these KRAS mutant cells have a set of conditional dependencies that can be exploited for therapeutic benefit. The three specific aims of this proposal are to 1) explore the cellular consequences of mutant KRAS loss 2) understand the mechanistic relationship between KRAS inhibitors and their effects on KRAS degradation and localization 3) identify genetic and pharmacological interactions that cooperate with KRAS loss. The results of this project are expected to help elucidate the biology of one of the most critical oncogenes in cancer and pinpoint combination therapies and susceptible genotypes with potential clinical utility. This research is expected to have a broad impact on therapy for a variety of cancer types, with a particular emphasis on personalized genotype-specific targeted medicine. My research focuses on elucidating the biological mechanisms driving cancers to advance frontline therapies and improve patient outcomes. I have proposed a comprehensive training and career development program for the mentored (K99) phase and my transition to independent principal investigator (R00). Research on the genetic model of mutant KRAS ablation in Aim 1A, the mechanism of KRAS degradation probed in Aim 2, and the CRISPRi and CRISPRa screens to look for cooperators with KRAS inhibition in Aim 3 are predicted to be completed during the K99 phase. The pharmacological effects on mutant KRAS biology in Aim 1B and biological validation and mechanistic illumination of screen hits from Aim 3 are scheduled for the R00 period. Components of my training program include 1) guidance from my esteemed mentor Dr. McCormick for all Aims, 2) regular meetings with an expert advisory panel, 3) career development courses at UCSF, 4) online learning resources such as the Ras Lab researcher forum, 5) hands-on training using state-of-the-art equipment and forefront technologies, and 6) conceptual learning from Dr. McCormick and my advisory team on planning and conducting experiments. This extensive research and professional development program will guide me during the mentored phase toward excelling as an independent academic principal investigator.